The present invention relates to a valve for an hydraulic ram, notably to a pile driver incorporating such a valved ram for moving the hammer of the pile driver.
In an hydraulic ram, as used in a pile driver, fluid must flow rapidly into and out of the ram cylinder in synchrony with the operation of the hammer. In order to achieve this flow, it has been proposed to use a spool valve. The spool is moved axially by applying fluid at pressure to one side or the other of the valve. However, this requires the use of extra fluid lines to feed fluid to the valve and complex sealing arrangements which are costly and cumbersome.